title: Short-term effects of potassium fertilization on the hydraulic conductance of Laurus nobilis L.
abstract: This study reports experimental evidence on the effect of short-term potassium fertilization on potassium uptake, tissue concentration and hydraulic conductance of pot-grown laurel plants. Potassium uptake and loading into the xylem of laurel seedlings increased within 24 h after fertilization. Potassium was not accumulated in roots and leaves, but the [K(+)] of xylem sap was 80% higher in fertilized plants (+K) than in potassium-starved plants (-K), as a likely result of recirculation between xylem and phloem. Increased xylem sap [K(+)] resulted in a 45% increase in transpiration rate, a 30% increase in plant hydraulic conductance (K(plant)) and a 120% increase in leaf-specific conductivity of the shoot (k(shoot)). We suggest that this increase was due to ion-mediated up-regulation of xylem hydraulics, possibly caused by the interaction of potassium ions with the pectic matrix of intervessel pits. The enhancement of hydraulic conductance following short-term potassium fertilization is a phenomenon that can be of advantage to plants for maintaining cell turgor, stomatal aperture and gas exchange rates under moderate drought stress. Our data provide additional support for the important role of potassium nutrition in agriculture and forestry.
authors.affiliation: Dipartimento di Scienze Botaniche, Università di Palermo, Via Archirafi 38, Palermo, Italy. oddoel@unipa.it
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Oddo
authors.forename: Simone
authors.initials: S
authors.lastname: Inzerillo
authors.forename: Francesca
authors.initials: F
authors.lastname: La Bella
authors.forename: Francesca
authors.initials: F
authors.lastname: Grisafi
authors.forename: Sebastiano
authors.initials: S
authors.lastname: Salleo
authors.forename: Andrea
authors.initials: A
authors.lastname: Nardini
mesh_terms: D005308:Fertilizers; D017136:Ion Transport; D027442:Laurus / Q000378:metabolism*; D052585:Phloem / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D011188:Potassium / Q000378:metabolism*; D036226:Seedlings / Q000378:metabolism; D052584:Xylem / Q000378:metabolism
chemical_list: D005308:Fertilizers; D011188:Potassium